Update/Fix Istioctl links and docs (#349)

* Update/Fix istioctl links in README.md

Update/Fix istioctl links to use install-istioctl-tool.md, which provides instructions for installing istioctl independent of Istio.

Signed-off-by: Jamie Longmuir <jlongmui@redhat.com>

* Update install-istioctl-tool.md to clarify steps and link to upstream doc

Signed-off-by: Jamie Longmuir <jlongmui@redhat.com>

* remove namespace from get istio command

Signed-off-by: Jamie Longmuir <jlongmui@redhat.com>

---------

Signed-off-by: Jamie Longmuir <jlongmui@redhat.com>

docs/README.md

@@ -265,7 +265,7 @@ When the `InPlace` strategy is used, the existing Istio control plane is replace
 
 Prerequisites:
 * Sail Operator is installed.
-* `istioctl` is [installed](common/istio-addons-integrations.md).
+* `istioctl` is [installed](common/install-istioctl-tool.md).
 
 Steps:
 1. Create the `istio-system` namespace.
@@ -341,7 +341,7 @@ When the `RevisionBased` strategy is used, a new Istio control plane instance is
 
 Prerequisites:
 * Sail Operator is installed.
-* `istioctl` is [installed](common/istio-addons-integrations.md).
+* `istioctl` is [installed](common/install-istioctl-tool.md).
 
 Steps:
 
@@ -479,7 +479,7 @@ You can use the Sail Operator and the Sail CRDs to manage a multi-cluster Istio
 
 ### Prerequisites
 
-- Install [istioctl](https://istio.io/latest/docs/setup/install/istioctl) and have it included in your `$PATH`.
+- Install [istioctl](common/install-istioctl-tool.md).
 - Two kubernetes clusters with external lb support. (If using kind, `cloud-provider-kind` is running in the background)
 - kubeconfig file with a context for each cluster.
 - Install the Sail Operator and the Sail CRDs to every cluster.

docs/common/install-istioctl-tool.md

@@ -8,8 +8,7 @@ operators to debug and diagnose Istio service mesh deployments.
 
 Use an `istioctl` version that is the same version as the Istio control plane 
 for the Service Mesh deployment. See [Istio Releases](https://github.com/istio/istio/releases) for a list of valid 
-releases, including Beta releases.
-
+releases, including Beta releases. 
 
 ### Procedure
 
@@ -24,7 +23,7 @@ the following command at the terminal:
 at the terminal:
 
     ```sh
-    $ oc -n istio-system get istio
+    $ oc get istio
     ```
 
 3. Install `istioctl` by running the following command at the terminal: 
@@ -47,6 +46,6 @@ at the terminal:
     ```sh
     $ istioctl version
     ```
-
+For more information on usage, see the [Istioctl documentation](https://istio.io/latest/docs/ops/diagnostic-tools/istioctl/).
 
 *Note*: `istioctl install` is not supported. The Sail Operator installs Istio.